The major objective is to elucidate fundamental mechanistic aspects of transcription, as well as transcriptional regulatory mechanisms, for genes whose activities are related to particular states of cell growth, proliferation, and differentiation. The genes to be analyzed include various human and amphibian (Xenopus) genes encoding 5S and tRNAs (class\III), rRNAs (class\I), and histone proteins (class\II). Having previously demonstrated accurate transcription initiation for a variety of genes (class I, II, and III) in systems reconstituted with crude extracts or with RNA polymerases and partially purified factors, we now propose for the genes of interest: (1)\to complete the delineation and purification of the respective transcription factors, including both general and regulatory (e.g., tissue or cell-stage specific) factors; (2)\to investigate in detail the sites and mechanisms of action of these factors (e.g., interactions with specific DNA sequences); (3)\to monitor alterations in the activities or levels of these factors during critical growth and developmental transitions (to correlate with gene activity); (4)\as part of the above, to analyze the structure and function of both natural and reconstituted (model) chromatin templates (in an effort to define factors which operate through chromatin structural modifications); (5)\as part of the above, to use site-directed mutagenesis to determine specific DNA sequences important for expression and regulation both in vivo and in vitro; (6)\as part of these studies, to employ in vivo gene transfer systems to analyze the expression and regulation of the various genes in vivo; and (7)\in conjunction with these studies, to continue the isolation and structural and functional analysis of both Xenopus and human histone genes, especially those which are cell-cycle regulated versus those which are expressed constituitively or only at certain developmental steps (e.g., during oogenesis or during the cessation of cell proliferation). These studies should provide fundamental information regarding transcriptional mechanisms in eucaryotes as well as insights into transcriptional controls which are operative during normal growth and development and which are altered in abnormal states such as neoplasia.